What's the deal with elevators?

[r.l.newman]

Could someone list or explain what exactly goes on when an elevator begins to accelerate and comes to a stop (both up and down) so that I can solve the problem below!

A person stands on a bathroom scale in a motionless elevator. When the elevator begins to move, the scale briefly reads only 0.88 of the person’s regular weight. Calculate the acceleration of the elevator. Find the direction of acceleration.

 

[Doc Al]

Some things to consider. If there were no elevator, the only force on the person would be his weight. He would accelerate downward at g, of course. The floor of the elevator holds the person up by exerting a force, the so-called normal force. It is that force that the scale reads. If there is no acceleration, then the forces on the person add to zero and the scale reads a force equal to the person's weight. But if the elevator accelerates upward, it must push with a greater force; if it accelerates downward, a lessor force.

As always, consider all the forces acting on the person and apply Newton's 2nd law. In these problems only two forces act: (1) the person's weight, and (2) the normal force of the elevator floor.

 

[M98Ranger]

Elevators are an essential part of modern buildings and are used to transport people and goods between different levels. They work on the principle of a counterweight system, where a motor and pulley system moves the elevator car up and down using a series of cables.

When an elevator begins to accelerate, the motor pulls the cables attached to the elevator car, causing it to move upwards or downwards. This acceleration is caused by the force of the motor pulling the elevator car, which in turn causes a change in the velocity of the car.

When the elevator is moving upwards, the person standing on the bathroom scale will experience a decrease in their weight due to the upward acceleration of the elevator. This is because the force of the motor is counteracting the force of gravity, resulting in a lower weight reading on the scale.

To calculate the acceleration of the elevator, we can use the formula a = (vf - vi)/t, where a is the acceleration, vf is the final velocity, vi is the initial velocity, and t is the time taken for the elevator to reach its final velocity. In this case, the initial velocity is 0 since the elevator was motionless, and the final velocity is the speed at which the elevator is moving when the scale reads 0.88 of the person's regular weight.

The direction of acceleration can be determined by the direction in which the elevator is moving. If the elevator is moving upwards, the acceleration will be positive, and if it is moving downwards, the acceleration will be negative.

In conclusion, elevators use a motor and pulley system to accelerate and transport people and goods between different levels. The acceleration of the elevator can be calculated using a simple formula, and the direction of acceleration depends on the direction in which the elevator is moving.